As an ecological foundation the American chestnut affected population, community and ecosystem processes in eastern American forests. Unfortunately, the American chestnut was extirpated as a canopy tree by the Chestnut blight (Cryphonectria parasitica (Murr.) Barr). fungus which was introduced in horticultural imports from Asia. In addition to providing tangible ecosystem services and a rich food source for wildlife, chestnut is a versatile tree for wood production and other agricultural products. Thus, the restoration of American chestnut (Castanea dentata) as a canopy dominant tree is important for ecological, economic and aesthetic reasons. One strategy to return American chestnut to its former range and ecological function, is to hybridize the American chestnut with the blight resistant Chinese chestnut Castanea mollisima. After 3 decades of backcrossing and careful selection, The American Chestnut Foundation (TACF) has created trees that are both blight resistant like Chinese chestnut and morphologically similar to the American chestnut. In addition to improved blight resistance, successful restoration depends on the physiological response of chestnuts to predicted climate change. However, little is known about the potential effects of climate change on the growth and physiology of American chestnuts or the enhanced blight resistant B3F3 hybrids.
Future predicted increases in global atmospheric CO2 concentration ([CO2]) will stimulate carbon uptake of most deciduous trees and thus forests as whole. Rising atmospheric [CO2] and emissions of other more potent greenhouse gases are predicted to increase global mean air temperatures by ≥ 3°C before the end of this century. Increasing temperatures may lengthen growing seasons and increase forest carbon storage, but the coupled impact of increasing atmospheric CO2 and increases in temperature (or other stresses) in forests are not fully resolved because different species respond in different ways.
Results/Conclusions
We will show that American chestnut photosynthesis exhibits local adaptation to high temperature as American chestnuts from the southern edge of the range have higher temperature optima, higher photosynthesis, and greater biomass when grown at elevated temperature and CO2. Interestingly, American chestnuts show greater stimulation of photosynthetic capacity and growth than hybrid chestnuts under elevated temperature and CO2.